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qapi: Split visit_end_struct() into pieces

Browse source 
As mentioned in previous patches, we want to call visit_end_struct()
functions unconditionally, so that visitors can release resources
tied up since the matching visit_start_struct() without also having
to worry about error priority if more than one error occurs.

Even though error_propagate() can be safely used to ignore a second
error during cleanup caused by a first error, it is simpler if the
cleanup cannot set an error.  So, split out the error checking
portion (basically, input visitors checking for unvisited keys) into
a new function visit_check_struct(), which can be safely skipped if
any earlier errors are encountered, and leave the cleanup portion
(which never fails, but must be called unconditionally if
visit_start_struct() succeeded) in visit_end_struct().

Generated code in qapi-visit.c has diffs resembling:

|@@ -59,10 +59,12 @@ void visit_type_ACPIOSTInfo(Visitor *v,
|         goto out_obj;
|     }
|     visit_type_ACPIOSTInfo_members(v, obj, &err);
|-    error_propagate(errp, err);
|-    err = NULL;
|+    if (err) {
|+        goto out_obj;
|+    }
|+    visit_check_struct(v, &err);
| out_obj:
|-    visit_end_struct(v, &err);
|+    visit_end_struct(v);
| out:

and in qapi-event.c:

@@ -47,7 +47,10 @@ void qapi_event_send_acpi_device_ost(ACP
|         goto out;
|     }
|     visit_type_q_obj_ACPI_DEVICE_OST_arg_members(v, &param, &err);
|-    visit_end_struct(v, err ? NULL : &err);
|+    if (!err) {
|+        visit_check_struct(v, &err);
|+    }
|+    visit_end_struct(v);
|     if (err) {
|         goto out;

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1461879932-9020-20-git-send-email-eblake@redhat.com>
[Conflict with a doc fixup resolved]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
This commit is contained in:
Eric Blake 2016-04-28 15:45:27 -06:00 • committed by Markus Armbruster
parent 56a6f02b8c
commit 15c2f669e3
18 changed files with 128 additions and 73 deletions
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35
qapi/qmp-input-visitor.c
View file

@ -125,9 +125,11 @@ static void qmp_input_push(QmpInputVisitor *qiv, QObject *obj, Error **errp)
}
static void qmp_input_pop(QmpInputVisitor *qiv, Error **errp)
static void qmp_input_check_struct(Visitor *v, Error **errp)
{
QmpInputVisitor *qiv = to_qiv(v);
StackObject *tos = &qiv->stack[qiv->nb_stack - 1];
assert(qiv->nb_stack > 0);
if (qiv->strict) {
@ -140,6 +142,20 @@ static void qmp_input_pop(QmpInputVisitor *qiv, Error **errp)
if (g_hash_table_iter_next(&iter, (void **)&key, NULL)) {
error_setg(errp, QERR_QMP_EXTRA_MEMBER, key);
}
}
}
}
static void qmp_input_pop(Visitor *v)
{
QmpInputVisitor *qiv = to_qiv(v);
StackObject *tos = &qiv->stack[qiv->nb_stack - 1];
assert(qiv->nb_stack > 0);
if (qiv->strict) {
GHashTable * const top_ht = qiv->stack[qiv->nb_stack - 1].h;
if (top_ht) {
g_hash_table_unref(top_ht);
}
tos->h = NULL;
@ -175,12 +191,6 @@ static void qmp_input_start_struct(Visitor *v, const char *name, void **obj,
}
}
static void qmp_input_end_struct(Visitor *v, Error **errp)
{
QmpInputVisitor *qiv = to_qiv(v);
qmp_input_pop(qiv, errp);
}
static void qmp_input_start_list(Visitor *v, const char *name, Error **errp)
{
@ -218,12 +228,6 @@ static GenericList *qmp_input_next_list(Visitor *v, GenericList **list,
return entry;
}
static void qmp_input_end_list(Visitor *v)
{
QmpInputVisitor *qiv = to_qiv(v);
qmp_input_pop(qiv, &error_abort);
}
static void qmp_input_start_alternate(Visitor *v, const char *name,
GenericAlternate **obj, size_t size,
@ -383,10 +387,11 @@ QmpInputVisitor *qmp_input_visitor_new(QObject *obj, bool strict)
v->visitor.type = VISITOR_INPUT;
v->visitor.start_struct = qmp_input_start_struct;
v->visitor.end_struct = qmp_input_end_struct;
v->visitor.check_struct = qmp_input_check_struct;
v->visitor.end_struct = qmp_input_pop;
v->visitor.start_list = qmp_input_start_list;
v->visitor.next_list = qmp_input_next_list;
v->visitor.end_list = qmp_input_end_list;
v->visitor.end_list = qmp_input_pop;
v->visitor.start_alternate = qmp_input_start_alternate;
v->visitor.type_int64 = qmp_input_type_int64;
v->visitor.type_uint64 = qmp_input_type_uint64;